While there were Iron Age and Roman settlements in the area now covered by the town, Rotherham itself was not founded until the Early Middle Ages. It soon established itself as a key Saxon market town, lying, as it does, on a Roman road near a forded part of the Don.

By the late Saxon period, Rotherham was at the centre of a large parish on both sides of the River Don. Following the Norman Conquest, an absentee lord, Nigel Fossard, was put in place. His successors the De Vescis also rarely visited the town and so did not build a castle or contribute to the town's civil life, but did maintain a Friday market and a fair. In the mid-thirteenth century, John de Vesci and Ralph de Tili gave all their possessions in Rotherham to Rufford Abbey. The monks collected tithes from the town and gained rights to add Monday as an additional market day and to extend the annual fair from two to three days